Unless someone un-suspends their campaign (wouldn't rule it out this year).

Bernie Sanders
Pete Buttigieg
Elizabeth Warren
Amy Klobuchar
Joe Biden
Michael Bloomberg
Tom Steyer
Tulsi Gabbard

I imagine Tulsi and Tom will drop out soon. The rest will probably stick around through super Tuesday.

Hard to say who else besides Bernie is a serious contender. I'd guess at least Pete is. I don't think he will do as poorly in the following states as pre-Iowa polls were showing.

Amy has potential but too early to say her momentum is real. Biden and Warren have the potential for bounce backs but I wouldn't bet on them. We need to see how Bloomberg does on super Tuesday, hopefully worse than Biden.

I wonder how many people would change their votes now. I am wavering on Warren, I need to see some life from her in NV. I am seriously considering changing to Bernie.